1. Field of the Invention
The present invention relates to a method of operating an access point and a wireless communication system using an access point.
2. Description of the Related Art
An access point (AP) is a device configured to connect wireless terminals to a wired device in a computer network using standards related to WiFi, Bluetooth, and so on, which may be referred to as a wireless access point (WAP).
Such an AP, which is generally connected to a router through a wired network, can transmit date between wireless terminals such as a smart phone, a tablet PC, a computer, a printer, etc., and a wired device in a network. Here, the wireless terminals can use various services such as a voice call service, a moving picture service, a date service, etc., through the AP.
Meanwhile, one AP can be connected to a plurality of terminals through wireless communication, and the wireless communication is performed according to types of services required by the plurality of terminals in different order of priorities.
For example, an online game, a video-telephony service, a voice call service, etc., which require data transmission in real time, are primarily processed, a moving picture service which may cause buffering, etc., is secondarily processed, and then, a general data service is processed.
Characteristics of the services, which become a standard for dividing order of priorities, are referred to as quality of service (QoS).
In addition, a conventional art widely uses a carrier sense multiple access/collision avoidance (CSMA/CA) method of detecting a carrier wafer using a medium before connection to the medium, and adjusting a communication sequence based on a sensed carrier such that collision between data communication does not occur.
That is, when a certain terminal requests communication with the AP, it is determined whether another terminal is already communicating with the AP through the CSMA/CA method, and the certain terminal is on standby. Accordingly, wireless communication can be performed by differentiating a standby time, in which the corresponding terminal requires communication to the AP again, into 1 ms in the case of the service requiring data transmission in real time, 2 ms in the case of the moving picture service, and 3 ms in the case of the general data service, according to the types of QoS.
However, such a method causes an increase in standby time of users who want to use another service, and thus, a fairness problem occurs. In addition, when the data communication is distributed to improve fairness, quality in voice call and video-telephony services requiring data communication in real time may be decreased.
In order to solve the problem, a technique employing a multiple input multiple output (MIMO) method has been proposed.
The MIMO method is a method of installing a plurality of antennae at transmission/reception terminals to increase a channel capacity in a given bandwidth and transmitting different transmission signals from transmission antennae. Accordingly, in comparison with a conventional single input single output (SISO) method, a data transmission rate gain and a channel capacity can be increased by the number of transmission antenna.
However, even when the MIMO method is applied, as the conventional CSMA/CA is used, all of the channels of the system cannot be utilized with optimized efficiency.